Thoughts on electrical issue

04 cobra, ~200k miles.

Sometimes when I key off the car the gauges will start to sweep to zero but freeze and the odometer will flash dashes (which I think means it lost connection with PCM).

At the same time when this started happening, every month or two (i.e., very infrequently) when I try to start the car I"ll hear a loud CLICK and then I'll lose all power to the car (everywhere, for example, no power windows or trunk, etc...). If I pull the key out of the ignition I hear a loud TICK TICK TICK coming from underneath the driver dash. If I stick the key back in the TICKing will stop, and resume if I remove the key. The only way I can get power back to the car is to disconnect the battery, wait a minute, then hook it back up. Then everything works perfectly, at least until it happens again.

I kinda think CCRM because of the odometer flashing dashes at me, but I don't think the CCRM would explain losing all power in the car when I try to start it. I kinda think something with the starter, like maybe it's shorting itself and that causes a circuit breaker to blow, but then it should be a consistent problem, not one that happens every month or two.

I would check main bat. power and grounds. A weak connection can "fail" when stressed (cranking).

No comment on the clicking...

Also check connections at the fuse panel under the dash.

grounds on radiator support.

I've had issues with the rings cracking and had issue with ground wire burning up inside casing..

I did replace ground wire from battery to support with a larger size battery wire..

the oem battery terminal' also wear after time..
if they have been replaced..like mine have..
these get dirty fast..and need a ot more cleaning than most..

I've had bad alts,bad batterys,these issues have only set battery light

I've replaced the battery so it can't be that. I did a voltage drop test on the connections and they seemed okay. Visually connections seem okay but I guess I shuld give them a cleaning, couldn't hurt.

visual doesn't work. I'd have a multi meter on hand and test during failure.

Do a visual on the ignition switch! The 2 halves start to separate and the internal contacts start to separate as well causing all sorts of weird issues. At that mileage grab a Motorcraft Ignition switch and replace the original.

SV

Had an issue like this. Ended up being a loose ground in the trunk connecting to the FPDM.